Re: Inventor Help
 

For a half sphere in Inventor, there are multiple ways to do it. On your sketch, you want to make a line (length doesn't matter as long as it intersects the arc that you are about to make). Then, make an arc with the radius that you want (ends up being the radius of the sphere). Make sure the center of the arc is coincident to the line.

There are several ways to go here:
1. Revolve the sketch you just made. I believe there is an option somewhere to tell it how far to go around and then enter 180 degrees. If this works, then great! You're done. If not, darn, but there is another way.
2. Revolve the sketch, and let it revolve all the way. Share the sketch that you made earlier, and make sure it is visible. Then click on extrude; make sure the area between the arc and the line is highlighted. Where it says distance, click the arrow and change it to all. Below that, there should be pictures of planes with arrows coming out of them. Click the one that has an arrow coming out of both sides. Make sure you are extruding away the piece, and click OK. Congrats, you're done!

HTH,
Daniel

Re: Inventor Help
 

to make a tetra-shaped pyramid, one could possibly draw four triangles - one equilateral on the bottom for the bottom, and three on the sides of the bottom at 90 degrees to it that are the vertical length and width of the sides. Extrude the bottom, say, 50 inches, and then extrude the sketches with the intersect option and through all selected (or specify a distance, I don't have inventor in fromt of me right now and can't remember.) I think that this will work.

Squirrel

Re: Inventor Help
 

This soulds easy, but might make more problems. Unless you know the exact shape of the other triangles in projection, you will get a bad shape. The side triangles are equalitateral but not if you look at the from the side. The would be squashed triangles.

Re: Inventor Help
 

Hey,

I figured out how to cut a rail for the robot, but i accidentally messed up the file that had it cut to size, now all i have is the smaller piece, now i want to make it to make it longer again, but when i do, the holes that in it every inch or so don't continue, the extension is just a plain rail ( no holes, can i extend them with holes?

Also when i try to go to the base file (unaltered) and i try to "Move Face" or "Extend or Contract body" it says the following:

Modeling failure in ASM. Redefine inputs.
Faces(s) could not be moved.

Does anyone know how to do either of these, whichever is easier?

Peter

Re: Inventor Help
 

How did you cut the peice? if you cut it with Split, then you just move the cutting plane to where you want it and it should update. Especially if you made the holes first. if you did a cut extrution, then you can change the sketch and it will probably update. If you did something different or theses don't work, then you can look at the sketch with the holes and copy the holes after you extend it. Still lacking? then you can do a rectangular array of the holes. select the hole's feature, select rectangular array (should be near the circualar aray and mirror tools) and select a line that goes in the direction that you want. set the number of holes and the distance between them and click OK. Or, if all else fails, you can make the holes manually.

With the assembly, it is probably complaining becuase there was a constraint or other setting. First try the Repair tool and follow the prompt to try and fix it. If not, ou can right click on the offending componate and say Re-Place componate. this will reset the file link and posably fix the problem. Or you could delete the componate and place it again.

Re: Inventor Help
 

You can retrieve a previous version of the file in the OldVersions folder (the one in the directory which your part file is in). I don't remember how many versions back it keeps, but it's worth a try to go back to a version before you cut the part.

Re: Inventor Help
 

The Old Versions Folder seems to keep, not previous versions of you model, but your model as formats old versions can open (eg. STEP). These might be old versions of your model, I haven't opened them, but there is only one STEP file (and one other file that apparently goes with the STEP file) for each item for me.

Re: Inventor Help
 

Actually, I believe it opens the last version previous to the currently saved version. So, if you have a file pSprocket.ipt, in the OldVersions folder you might find a part file pSprocket.0016. When you open the old part file, you will be presented with a dialog giving you choices of Open old version, Restore old version to current or Open current version.

I haven't found any setting for the number of previous versions it keeps, so it appears you can only go back to before you last saved.

Re: Inventor Help
 

Now that build season is over I am expected to make a detailed 3D model of our completed bot. I already have a model of our bot when it was about 1/2 finished and it slows down even the Dell XPS that we have. Does anyone know of anyway that would make the best use of RAM (without comprimising too much detail) or making the process go faster.

Re: Inventor Help
 

I don't know how you will get an accurate model of the robot when it's in the box in storage. I wish you luck and email me at jdiwnab at gmail dot com if I can get you some part.

Reguarding you computer issue, I don't know what is in that computer. I have a 1.9GHz AMD with 768MB RAM at it olnly really slows up when I try to get a complex array (like when I was doing the tread last night (190 instances:mad:)) or if I am trying to import a CD in iTunes in the background. There might be some settings to lower the level of detail the Inventor displays (like the shiny reflections on chrome) but their isn't much you can do. Inventor just takes up a lot of power. If there is another computer available to you, try to move to it.

Re: Inventor Help
 

This is a chronic problem when building an Inventor model with a lot of multi-featured parts. Here are some things which may help:

1. You can never have too much RAM or too good a graphics card. 1 GB is the practical minimum for large assembly modelling. You will need an OpenGL compliant graphics card with as much on-board video RAM as you can afford. The latter is especially important when you do constraint-driven animations of large assemblies. Another factor here: whenever possible, run just the CAD application; log out of IM, kill your Internet browser, etc. Every little bit helps.

2. Divide and conquer: Divide the robot into sub-assemblies, such as chassis, gripper, arm, etc. and complete them separately as much as possible before putting them together for the full robot assembly.

3. The devil is in the details: Use simplified models of things like gears, chains and other commercial components which have a zillion features and surfaces. For gears, make a model which has all of the gear's features except the teeth. For chains, make a solid "belt" which shows the path and space occupied by the chain. Add fine details like screws, nuts, etc. only after you have all your parts finished.

4. Stay with a plain background in your modeling display. To reduce the load on your graphics card, avoid putting a pretty picture in as your background until you are ready to do your screenshots.

Lastly, Be Patient. When you work with the whole robot assembly model, expect the file to take several minutes to open, and take the time save your work frequently.

Re: Inventor Help
 

Thanks for the help, I will give these methods a go. I checked up on the hardware on our computer and i found out that it had 2G of RAM. That is more than I knew could be put on.

I havn't even started with gears and chains yet and I'm not looking forward to it. I have to mess with the cable/harness feature. If anybody has any tips regarding cables please help me.

All that I know is what I have taught myself through the tutorials (nobody at my school had ever heard of Inventor).

Thanks a million.

Re: Inventor Help
 

I am struggling with both chain and wires. I had XP SP2 and had to unstall it even to get any wiring to work. I think Inventor 8 pro is built of NT or somthing, beucase it donesn't work well with XP.

As far as chain goes, I found a thread about it that had a link to download real chain. But you must constrain it link by link and then find some way of putting it on you bot. I think that some shiny and bumpy band will do it. See How much more complicated yet better looking the real chain is?

On wires, I couldn't get real wires to route so I used segments to trace out the path then adjusted how they looked to take the place of wires.

I used the same painstaking method to make the rope we used on things

Re: Inventor Help
 

How would you constrain them so that they would actually turn when you moved the arm, or is there a way to do that at all?

Re: Inventor Help
 

The chain was for are drive system. I haven't gotton the realish chain to fit on the sprockets right, but the fakish chain is just a static band. We didn't use chain for are arm. If the chain you plan on using is a straight loop (like in drive and simple arms, not the expanding arms that seem to work so great), then just make a loop with the bumps like I did.